Microbiological diagnosis and mortality of tuberculosis meningitis: Systematic review and meta-analysis

Background Tuberculosis (TB) which is caused by Mycobacterium tuberculosis poses a significant public health global treat. Tuberculosis meningitis (TBM) accounts for approximately 1% of all active TB cases. The diagnosis of Tuberculosis meningitis is notably difficult due to its rapid onset, nonspecific symptoms, and the difficulty of detecting Mycobacterium tuberculosis in cerebrospinal fluid (CSF). In 2019, 78,200 adults died of TB meningitis. This study aimed to assess the microbiological diagnosis TB meningitis using CSF and estimated the risk of death from TBM. Methods Relevant electronic databases and gray literature sources were searched for studies that reported presumed TBM patients. The quality of included studies was assessed using the Joanna Briggs Institute Critical Appraisal tools designed for prevalence studies. Data were summarized using Microsoft excel ver 16. The proportion of culture confirmed TBM, prevalence of drug resistance and risk of death were calculated using the random-effect model. Stata version 16.0 was used perform the statistical analysis. Moreover, subgroup analysis was conducted. Results After systematic searching and quality assessment, 31 studies were included in the final analysis. Ninety percent of the included studies were retrospective studies in design. The overall pooled estimates of CSF culture positive TBM was 29.72% (95% CI; 21.42–38.02). The pooled prevalence of MDR-TB among culture positive TBM cases was 5.19% (95% CI; 3.12–7.25). While, the proportion of INH mono-resistance was 9.37% (95% CI; 7.03–11.71). The pooled estimate of case fatality rate among confirmed TBM cases was 20.42% (95%CI; 14.81–26.03). Based on sub group analysis, the pooled case fatality rate among HIV positive and HIV negative TBM individuals was 53.39% (95%CI; 40.55–66.24) and 21.65% (95%CI;4.27–39.03) respectively. Conclusion Definite diagnosis of TBM still remains global treat. Microbiological confirmation of TBM is not always achievable. Early microbiological confirmation of TBM has great importance to reduce mortality. There was high rate of MDR-TB among confirmed TBM patients. All TB meningitis isolates should be cultured and drug susceptibility tested using standard techniques.


Introduction
was assessed as high if >80%, medium if 60-80%, and low if <60%. Two authors (GS and BD) 116 carried out the quality assessment, while the third author handled the disagreement between the 117 two authors (AA).

Study characteristics 136
There were 14 studies from Asia, eight from Europe, five from America, and only four (20,26,137 27, and 36) studies from Africa (3 in South Africa and one in Uganda) . Ninety percent of the 138 included studies were retrospective studies in design. The study period of the studies was from 139 1985 to the earliest 2020. The range of sample sizes was 20(23) to 6762(36) study participants. 140 Five studies (18, 20, 25, and 27, 32) were conducted on children under the age of 18 and seven 141 studies were conducted on adults over the age of 18. The rest studies included all study participants without discrimination on age. The total study participants of the included studies 143 were 20,596 (Table 1). 144 Quality assessments of the included studies are provided in the supporting information (S. Table   145 2).Ten studies (19, 21, 22,23,28,30,33,34,38 and 47) score medium quality based on JBI quality 146 assessment checklist for prevalence studies. While most of the studies score high quality using 147 JBI checklist for prevalence studies.

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Only fourteen studies reported the drug resistance pattern of the CSF culture-positive isolates. A 155 total of 2736 CSF Mycobacterium TB culture-positive isolates were tested for drug 156 susceptibility. Fourteen studies(5 from india,4 from china,2 from south Africa,1 from America,1 157 from Peru and 1 from Veitnam) were included to analyses the drug resistance pattern. MDR-158 TBM was found in 5.19 % of these isolates (95% CI: 3.12-7.25). (Fig.4).Eight studies reported 159 the proportion of INH mono resistance from the above total isolates. INH mono-resistance was 160 9.37 % (95% CI; 7.03-11.71) (Fig.5 In this systematic review and meta-analysis the microbiological diagnosis of Tuberculosis 174 meningitis and the risk of death among patients were calculated. According to the data around 175 one-third of TBM patients had CSF microbiological (TB culture and AFB microscopy) 176 confirmed illness. MDR-TB was found to be prevalent in TBM patients. The risk of death was 177 significant among TB meningitis patients. As per the findings, one patient will die for every five 178 TBM cases.

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The culture confirmed diagnostic rate reported in this study (29.72%) was slightly near to the 180 report (38.9%) of a previous study (49). It implies that three-fourth of TBM patients were got 181 anti-TB treatment empirically. This finding was also in support with the reports of previous 182 study which stated as in more than 50 per cent TBM patients, microbiological confirmation is not   The lower positivity of CSF for Mycobacterium tuberculosis based on AF smear microscopy 198 found in this meta-analysis was similar to other studies report which describe staining of CSF smears for acid-fast bacilli has poor sensitivity (about 10% to 15%) (54). However, Smear 200 microscopy is the most widely used rapid and inexpensive diagnostic test for TB, especially in 201 low and middle-income countries. Based on this most TBM cases were not microbiologically 202 confirmed.

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This systematic review and meta-analysis study has shown that drug resistance in TBM is not an 204 unusual occasion. The rate of MDR-TB and INH mono resistance was 5.19% and 9.37% 205 respectively. Since most of the included studies to analyze drug resistance pattern were from 206 Asia (5 from India, 4 from china and 1 from Vietnam), the result reflects drug resistance pattern 207 in that specific region. This indicates that TBM has a high vulnerability to drug resistance. Thus different mortality rate reported in this study among children and adults was against the reports 217 of a previous single study (56) which reports a similar 7.03% mortality rate in both groups. This 218 finding (mortality rate among children 9.8%) is lower than the report of previous systematic 219 review and meta-analysis (57). which reported 19.3% mortality rate among children. It might be 220 due to the previous study participants were HIV -infected children. Among adults, our study 221 finding was consistent with the previous studies (49, 55).

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According to this study, HIV-TBM co-infected individuals have a two-fold greater mortality rate 223 than HIV-negative patients; mortality in HIV-negative TBM patients was 21.65%, compared to particularly at a stage of more advanced immunosuppression (57). It has been reported that tuberculosis patients co-infected with HIV were more likely to have poor treatment outcomes 229 and death (58, 59).

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There was a lot of heterogeneity between studies. We were able to find subgroup analysis based 231 on the features of the included research, but we still don't know what caused the heterogeneity.

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Although we were unable to pinpoint the source of heterogeneity, the following factors could 233 contribute to publication bias and heterogeneity: 1).We only considered research that was 234 published in English; 2).the smallest sample size of the included studies was 20; and 3).the 235 majority of the studies were retrospective.

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Our study has some limitations: First, in this meta-analysis, we only included studies published 237 in English. Second, studies that did not use the gold standard TB culture for diagnosis were 238 excluded. Third, due to in availability of data we cannot analyse mortality by Anti-retroviral      2 Selection process 8 Specify the methods used to decide whether a study met the inclusion criteria of the review, including how many reviewers screened each record and each report retrieved, whether they worked independently, and if applicable, details of automation tools used in the process.
2 Data collection process 9 Specify the methods used to collect data from reports, including how many reviewers collected data from each report, whether they worked independently, any processes for obtaining or confirming data from study investigators, and if applicable, details of automation tools used in the process.

Item # Checklist item
The location where item is reported assessment to missing results in a synthesis (arising from reporting biases).
Certainty assessment 15 Describe any methods used to assess certainty (or confidence) in the body of evidence for an outcome.

Study selection
16a Describe the results of the search and selection process, from the number of records identified in the search to the number of studies included in the review, ideally using a flow diagram.

4
16b Cite studies that might appear to meet the inclusion criteria, but which were excluded, and explain why they were excluded.  Since the operational definition is still ambiguous we want to omit from the manuscript.
6.The discussion requires additional details on the limitations -you may either include these as you discuss the findings or expand the limitations paragraph. These should include: -trained personnel -for what taking CSF, testing CSF, where is this limited? Any publications that confirm this?
 In the discussion section we added some discussion on trained personnel and limited skill on taking CSF from lumbar puncture with references. See page 7 line 186-191 -Rate of DR TB -this was only possible in subset of n=XX studies. Also check was these in a particular region and does this DR TB rate reflect underlying DR TB pattern in that region?
Response to Reviewers  The following sentence is added to the discussion part under rate of MDR-TB.'…Since most of the included studies to analyze drug resistance pattern were from Asia (5 from India, 4 from china and 1 from Vietnam), the result reflects drug resistance pattern in that specific region.
-HIV TBM mortality -study not able to stratify by CD4 count or ART use; also comment on the study period, could the high HIV TBM be because it occurred in period prior to widespread ART?